单核及双核叔铵盐离子液体的合成及用于柠檬酸三丁酯的制备

合成了具有Bronsted酸性的单核叔铵盐离子液体1-(丙酸基)高哌啶硫酸氢盐HMILS]HSO4和双核叔铵盐离子液体双-(1-高哌啶)亚丁基双硫酸氢盐HMIBLHSO4]2，用红外、核磁、元素分析及热分析等方法对合成的产物进行表征。把合成的单核及双核酸性离子液体作为催化剂用于催化柠檬酸和正丁醇的酯化反应，考察其催化活性。结果表明，离子液体的催化活性与其酸强度呈相关性，其中双核离子液体HMIBLHSO4]2具有较强的酸性和较高的催化活性，当反应条件为n(正丁醇)∶n(柠檬酸)∶n(HMIBLHSO4]2)=5∶1∶0.05、120℃、反应时间3h，柠檬酸的转化率和柠檬酸三丁酯的选择性分别为98.91%和99.53%，反应后的酸性离子液体可以回收，稳定性好，重复使用10次后仍有较高的催化活性。

Synthesis of uni-nuclear and bi-nuclear tertiary ammonium ionic liquids used for preparation of tributyl citrate

Bronsted acidic ionic liquid 1-(propionyloxy) high piperidine hydrogen sulfate (HMILS] HSO4) and bis-(1-high piperidine) butylidene double hydrogen sulfate (HMIBLHSO4]2) were synthesized and characterized by FT-IR，1H NMR，elemental analysis and thermal analysis. As uni-nuclear and bi-nuclear tertiary ammonium ionic liquids，they were used in the esterification reaction of citric acid with n-butyl alcohol for investigating their catalytic activity. The catalytic activity of ionic liquids was related to its acidity，and HMIBLHSO4]2 had higher acidity and catalytic activity. Conversion of citric acid and selectivity to TBC were 98.91% and 99.53% respectively under the reaction conditions of n(alcohol)∶n(acid)∶n(IL)=5∶1∶0.05，temperature 120℃，reaction time 3h. Acidic ionic liquid could be recycled and exhibit high stability upon reusage. It still remained highly active even after being resued for ten times.